1. Field of the Invention
The present invention relates to a mobile terminal capable of receiving mobile broadcast services. More particularly, the present invention relates to a mobile terminal that can output broadcast data using a broadcast transmission scheme providing a sleep interval between consecutive frames carrying broadcast data, and a channel switching control method based on channel information update in the mobile terminal.
2. Description of the Related Art
A mobile broadcast service enables mobile terminals (e.g., cellular phones, laptop computers, personal digital assistants, and the like) to receive broadcast data. A user carrying a mobile terminal capable of receiving a mobile broadcast service may receive a desired broadcast at most times and places.
Examples of mobile broadcast systems providing broadcast services to mobile terminals include a Digital Multimedia Broadcasting (DMB) system, a Digital Video Broadcasting-Handheld (DVB-H) system, a Media Forward Link Only (FLO) system, and a Advanced Television System Committee-Mobile/Handheld (ATSC-MH) system. More particularly, the ATSC-MH system is employed mainly in North America including the USA, and specifies a sleep interval between consecutive frames carrying broadcast data.
More specifically, the ATSC-MH broadcasting system has an attribute referred to as a Parade Repetition Cycle (PRC), which specifies periodic transmission of broadcast data in units of frames of 0.968 seconds. A sleep interval of zero or several seconds is present between consecutive frames. In the ATSC-MH broadcasting system, multiple broadcasters may own specific frequency bands and broadcast transmitters of a single broadcaster may be located at different regions.
When the user issues a channel switch request during reception of a mobile broadcast service through a mobile broadcast system, the mobile terminal performs channel switching using stored channel information. A description is given below of a procedure for channel switching with reference to FIG. 1.
FIG. 1 is a flowchart illustrating a method for channel switching according to the related art.
Referring to FIG. 1, the mobile terminal enters into a mobile broadcast service mode for outputting broadcast data in step 110. The mobile terminal outputs broadcast data received through frequency corresponding to a channel selected by the user in step 120. The mobile terminal determines whether a channel switch request is issued in step 130.
When a channel switch request is issued, the mobile terminal conducts scanning for frequency corresponding to a newly selected channel in step 140. The mobile terminal analyzes a frame carried by the scanned frequency in step 150. The mobile terminal detects channel information in the analyzed frame in step 160. Here, the channel information describes broadcast data on the corresponding channel, and may be composed of text, speech and image data.
The mobile terminal displays the detected channel information in step 170. The mobile terminal tunes to the frequency corresponding to a channel selected by the user from the displayed channel information, and outputs broadcast data carried by the tuned frequency in step 180. Thereafter, the mobile terminal determines whether a request for terminating the mobile broadcast service mode is issued in step 190. When a request for terminating the mobile broadcast service mode is not issued, the mobile terminal returns to step 130.
In a case of the ATSC-MH system, one second is needed to receive one frame in frequency scanning for channel switching, and a frame carrying particular data is transmitted once for several seconds according to a given PRC. Hence, the mobile terminal may take a long time to display updated channel information. In addition, when the signal level of frequency corresponding to the target channel is not acceptable, the mobile terminal may be unable to provide a desired mobile broadcast service. In this case, the user may request another channel switch, and the channel switch may take additional time for channel switching until a desired mobile broadcast service is provided. For example, for conducting frequency scanning in relation to individual channels and displaying channel information, Terrestrial DMB (T-DMB), One-seg and ATSC-MH systems may take about 10 seconds, about 50 seconds and about 60 seconds, respectively. Hence, the user is inconvenienced by having to wait until updated channel information is displayed.
Therefore, a need exists for an apparatus and method for reducing the time for receiving updated channel information during channel switching in a mobile broadcast service.